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  • 1. Dosio, Alessandro
    et al.
    Jones, Richard G.
    Jack, Christopher
    Lennard, Christopher
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Hewitson, Bruce
    What can we know about future precipitation in Africa?: Robustness, significance and added value of projections from a large ensemble of regional climate models2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 53, no 9-10, p. 5833-5858Article in journal (Refereed)
  • 2. Tangang, Fredolin
    et al.
    Santisirisomboon, Jerasorn
    Juneng, Liew
    Salimun, Ester
    Chung, Jingxiang
    Supari, Supari
    Cruz, Faye
    Ngai, Sheau Tieh
    Ngo-Duc, Thanh
    Singhruck, Patama
    Narisma, Gemma
    Santisirisomboon, Jaruthat
    Wongsaree, Waranyu
    Promjirapawat, Kamphol
    Sukamongkol, Yod
    Srisawadwong, Ratchanan
    Setsirichok, Damrongrit
    Phan-Van, Tan
    Aldrian, Edvin
    Gunawan, Dodo
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, Hongwei
    Projected future changes in mean precipitation over Thailand based on multi-model regional climate simulations of CORDEX Southeast Asia2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, no 14, p. 5413-5436Article in journal (Refereed)
  • 3. Tamoffo, Alain T.
    et al.
    Moufouma-Okia, Wilfran
    Dosio, Alessandro
    James, Rachel
    Pokam, Wilfried M.
    Vondou, Derbetini A.
    Fotso-Nguemo, Thierry C.
    Guenang, Guy Merlin
    Kamsu-Tamo, Pierre H.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Longandjo, Georges-Noel
    Lennard, Christopher J.
    Bell, Jean-Pierre
    Takong, Roland R.
    Haensler, Andreas
    Tchotchou, Lucie A. Djiotang
    Nouayou, Robert
    Process-oriented assessment of RCA4 regional climate model projections over the Congo Basin under 1.5. C and 2. C global warming levels: influence of regional moisture fluxes2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 53, no 3-4, p. 1911-1935Article in journal (Refereed)
  • 4. Paprotny, D.
    et al.
    Morales-Napoles, O.
    Vousdoukas, M. I.
    Jonkman, S. N.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Accuracy of pan-European coastal flood mapping2019In: Journal of Flood Risk Management, ISSN 1753-318X, E-ISSN 1753-318X, Vol. 12, no 2, article id UNSP e12459Article in journal (Refereed)
  • 5. Endris, Hussen Seid
    et al.
    Lennard, Christopher
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Artan, Guleid A.
    Future changes in rainfall associated with ENSO, IOD and changes in the mean state over Eastern Africa2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, no 3-4, p. 2029-2053Article in journal (Refereed)
  • 6. Kamarainen, Matti
    et al.
    Hyvarinen, Otto
    Vajda, Andrea
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    van Meijgaard, Erik
    Teichmann, Claas
    Jacob, Daniela
    Gregow, Hilppa
    Jylha, Kirsti
    Estimates of Present-Day and Future Climatologies of Freezing Rain in Europe Based on CORDEX Regional Climate Models2018In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, no 23, p. 13291-13304Article in journal (Refereed)
  • 7. Angel Gaertner, Miguel
    et al.
    Jesus Gonzalez-Aleman, Juan
    Romera, Raquel
    Dominguez, Marta
    Gil, Victoria
    Sanchez, Enrique
    Gallardo, Clemente
    Marcello Miglietta, Mario
    Walsh, Kevin J. E.
    Sein, Dmitry V.
    Somot, Samuel
    Dell'Aquila, Alessandro
    Teichmann, Claas
    Ahrens, Bodo
    Buonomo, Erasmo
    Colette, Augustin
    Bastin, Sophie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Simulation of medicanes over the Mediterranean Sea in a regional climate model ensemble: impact of ocean-atmosphere coupling and increased resolution2018In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 51, no 3, p. 1041-1057Article in journal (Refereed)
  • 8.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Chris
    Dosio, Alessandro
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Chen, Youmin
    Haensler, Andreas
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Laprise, Rene
    Mariotti, Laura
    Maule, Cathrine Fox
    van Meijgaard, Erik
    Panitz, Hans-Juergen
    Scinocca, John F.
    Somot, Samuel
    The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065003Article in journal (Refereed)
  • 9. Maure, G.
    et al.
    Pinto, I.
    Ndebele-Murisa, M.
    Muthige, M.
    Lennard, C.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, A.
    Meque, A.
    The southern African climate under 1.5 degrees C and 2 degrees C of global warming as simulated by CORDEX regional climate models2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065002Article in journal (Refereed)
  • 10. Osima, Sarah
    et al.
    Indasi, Victor S.
    Zaroug, Modathir
    Endris, Hussen Seid
    Gudoshava, Masilin
    Misiani, Herbert O.
    Nimusiima, Alex
    Anyah, Richard O.
    Otieno, George
    Ogwang, Bob A.
    Jain, Suman
    Kondowe, Alfred L.
    Mwangi, Emmah
    Lennard, Chris
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, Alessandro
    Projected climate over the Greater Horn of Africa under 1.5 degrees C and 2 degrees C global warming2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065004Article in journal (Refereed)
  • 11. Lennard, C. J.
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, A.
    Moufouma-Okia, W.
    On the need for regional climate information over Africa under varying levels of global warming2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 060401Article in journal (Refereed)
  • 12. Klutse, Nana Ama Browne
    et al.
    Ajayi, Vincent O.
    Gbobaniyi, Bode
    SMHI, Professional Services.
    Egbebiyi, Temitope S.
    Kouadio, Kouakou
    Nkrumah, Francis
    Quagraine, Kwesi Akumenyi
    Olusegun, Christiana
    Diasso, Ulrich
    Abiodun, Babatunde J.
    Lawal, Kamoru
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Christopher
    Dosio, Alessandro
    Potential impact of 1.5 degrees C and 2 degrees C global warming on consecutive dry and wet days over West Africa2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 5, article id 055013Article in journal (Refereed)
  • 13. Mba, Wilfried Pokam
    et al.
    Longandjo, Georges-Noel T.
    Moufouma-Okia, Wilfran
    Bell, Jean-Pierre
    James, Rachel
    Vondou, Derbetini A.
    Haensler, Andreas
    Fotso-Nguemo, Thierry C.
    Guenang, Guy Merlin
    Tchotchou, Angennes Lucie Djiotang
    Kamsu-Tamo, Pierre H.
    Takong, Ridick R.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Christopher J.
    Dosio, Alessandro
    Consequences of 1.5 degrees C and 2 degrees C global warming levels for temperature and precipitation changes over Central Africa2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 5, article id 055011Article in journal (Refereed)
  • 14.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Ole Bossing
    Jacob, Daniela
    Keuler, Klaus
    Lenderink, Geert
    van Meijgaard, Erik
    Schar, Christoph
    Somot, Samuel
    Sorland, Silje Lund
    Teichmann, Claas
    Vautard, Robert
    European climate change at global mean temperature increases of 1.5 and 2 degrees C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models2018In: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 9, no 2, p. 459-478Article in journal (Refereed)
  • 15. Laiti, L.
    et al.
    Mallucci, S.
    Piccolroaz, S.
    Bellin, A.
    Zardi, D.
    Fiori, A.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Majone, B.
    Testing the Hydrological Coherence of High-Resolution Gridded Precipitation and Temperature Data Sets2018In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 54, no 3, p. 1999-2016Article in journal (Refereed)
  • 16. Akinsanola, A. A.
    et al.
    Ajayi, V. O.
    Adejare, A. T.
    Adeyeri, O. E.
    Gbode, I. E.
    Ogunjobi, K. O.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Abolude, A. T.
    Evaluation of rainfall simulations over West Africa in dynamically downscaled CMIP5 global circulation models2018In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 132, no 1-2, p. 437-450Article in journal (Refereed)
  • 17. Pucik, Tomas
    et al.
    Groenemeijer, Pieter
    Raedler, Anja T.
    Tijssen, Lars
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Prein, Andreas F.
    van Meijgaard, Erik
    Fealy, Rowan
    Jacob, Daniela
    Teichmann, Claas
    Future Changes in European Severe Convection Environments in a Regional Climate Model Ensemble2017In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 30, no 17, p. 6771-6794Article in journal (Refereed)
  • 18. Iqbal, W.
    et al.
    Syed, F. S.
    Sajjad, H.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Hannachi, A.
    Mean climate and representation of jet streams in the CORDEX South Asia simulations by the regional climate model RCA42017In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 129, no 1-2, p. 1-19Article in journal (Refereed)
  • 19. Knist, Sebastian
    et al.
    Goergen, Klaus
    Buonomo, Erasmo
    Christensen, Ole Bossing
    Colette, Augustin
    Cardoso, Rita M.
    Fealy, Rowan
    Fernandez, Jesus
    Garcia-Diez, Markel
    Jacob, Daniela
    Kartsios, Stergios
    Katragkou, Eleni
    Keuler, Klaus
    Mayer, Stephanie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Soares, Pedro M. M.
    Sobolowski, Stefan
    Szepszo, Gabriella
    Teichmann, Claas
    Vautard, Robert
    Warrach-Sagi, Kirsten
    Wulfmeyer, Volker
    Simmer, Clemens
    Land-atmosphere coupling in EURO-CORDEX evaluation experiments2017In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 122, no 1, p. 79-103Article in journal (Refereed)
  • 20.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Nilsson, Carin
    Lunds Universitet.
    Persson, Gunn
    SMHI, Professional Services.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Production and use of regional climate model projections – A Swedish perspective on building climate services2016In: Climate Services, ISSN 2405-8807, no 2-3, p. 15-29Article in journal (Refereed)
  • 21.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Borris, Matthias
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Foster, Kean
    SMHI, Research Department, Hydrology.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Persson, Magnus
    Perttu, Anna-Maria
    Uvo, Cintia B.
    Viklander, Maria
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Hydrological Climate Change Impact Assessment at Small and Large Scales: Recent Progress and Current Issues.2016In: Climate, ISSN 2225-1154, Vol. 4(3), no 39Article in journal (Refereed)
  • 22. Gampe, David
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Ludwig, Ralf
    Using an ensemble of regional climate models to assess climate change impacts on water scarcity in European river basins2016In: SCIENCE OF THE TOTAL ENVIRONMENT, ISSN 0048-9697, Vol. 573, p. 1503-1518Article in journal (Refereed)
  • 23. Gutowski, William J., Jr.
    et al.
    Giorgi, Filippo
    Timbal, Bertrand
    Frigon, Anne
    Jacob, Daniela
    Kang, Hyun-Suk
    Raghavan, Krishnan
    Lee, Boram
    Lennard, Christopher
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    O'Rourke, Eleanor
    Rixen, Michel
    Solman, Silvina
    Stephenson, Tannecia
    Tangang, Fredolin
    WCRP COordinated Regional Downscaling EXperiment (CORDEX): a diagnostic MIP for CMIP62016In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 9, no 11, p. 4087-4095Article in journal (Refereed)
  • 24. Casanueva, A.
    et al.
    Kotlarski, S.
    Herrera, S.
    Fernandez, J.
    Gutierrez, J. M.
    Boberg, F.
    Colette, A.
    Christensen, O. B.
    Goergen, K.
    Jacob, D.
    Keuler, K.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Teichmann, C.
    Vautard, R.
    Daily precipitation statistics in a EURO-CORDEX RCM ensemble: added value of raw and bias-corrected high-resolution simulations2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 47, no 3-4, p. 719-737Article in journal (Refereed)
  • 25.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Borris, Matthias
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Foster, Kean
    SMHI, Research Department, Hydrology.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Persson, Magnus
    SMHI.
    Perttu, Anna-Maria
    Uvo, Cintia B.
    Viklander, Maria
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Hydrological Climate Change Impact Assessment at Small and Large Scales: Key Messages from Recent Progress in Sweden2016In: CLIMATE, ISSN 2225-1154, Vol. 4, no 3, article id 39Article in journal (Refereed)
  • 26. Stensgaard, Anna-Sofie
    et al.
    Booth, Mark
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    McCreesh, Nicky
    Combining process-based and correlative models improves predictions of climate change effects on Schistosoma mansoni transmission in eastern Africa2016In: GEOSPATIAL HEALTH, ISSN 1827-1987, Vol. 11, p. 94-101Article in journal (Refereed)
  • 27. Leedale, Joseph
    et al.
    Tompkins, Adrian M.
    Caminade, Cyril
    Jones, Anne E.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Morse, Andrew P.
    Projecting malaria hazard from climate change in eastern Africa using large ensembles to estimate uncertainty2016In: GEOSPATIAL HEALTH, ISSN 1827-1987, Vol. 11, p. 102-114Article in journal (Refereed)
  • 28. Endris, Hussen Seid
    et al.
    Lennard, Christopher
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Teleconnection responses in multi-GCM driven CORDEX RCMs over Eastern Africa2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 9-10, p. 2821-2846Article in journal (Refereed)
  • 29. Pinto, Izidine
    et al.
    Lennard, Christopher
    Tadross, Mark
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Shongwe, Mxolisi E.
    Evaluation and projections of extreme precipitation over southern Africa from two CORDEX models2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 135, no 3-4, p. 655-668Article in journal (Refereed)
  • 30. Tobin, Isabelle
    et al.
    Jerez, Sonia
    Vautard, Robert
    Thais, Francoise
    van Meijgaard, Erik
    Prein, Andreas
    Deque, Michel
    Kotlarski, Sven
    Maule, Cathrine Fox
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Noel, Thomas
    Teichmann, Claas
    Climate change impacts on the power generation potential of a European mid-century wind farms scenario2016In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, no 3, article id 034013Article in journal (Refereed)
    Abstract [en]

    Wind energy resource is subject to changes in climate. To investigate the impacts of climate change on future European wind power generation potential, we analyze a multi-model ensemble of the most recent EURO-CORDEX regional climate simulations at the 12 km grid resolution. We developed a mid-century wind power plant scenario to focus the impact assessment on relevant locations for future wind power industry. We found that, under two greenhouse gas concentration scenarios, changes in the annual energy yield of the future European wind farms fleet as a whole will remain within +/- 5% across the 21st century. At country to local scales, wind farm yields will undergo changes up to 15% in magnitude, according to the large majority of models, but smaller than 5% in magnitude for most regions and models. The southern fleets such as the Iberian and Italian fleets are likely to be the most affected. With regard to variability, changes are essentially small or poorly significant from subdaily to interannual time scales.

  • 31. Favre, Alice
    et al.
    Philippon, Nathalie
    Pohl, Benjamin
    Kalognomou, Evangelia-Anna
    Lennard, Christopher
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, Alessandro
    Panitz, Hans-Juergen
    Cerezo-Mota, Ruth
    Spatial distribution of precipitation annual cycles over South Africa in 10 CORDEX regional climate model present-day simulations2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 5-6, p. 1799-1818Article in journal (Refereed)
    Abstract [en]

    This study presents an evaluation of the ability of 10 regional climate models (RCMs) participating in the COordinated Regional climate Downscaling Experiment-Africa to reproduce the present-day spatial distribution of annual cycles of precipitation over the South African region and its borders. As found in previous studies, annual mean precipitation is quasi-systematically overestimated by the RCMs over a large part of southern Africa south of about 20A degrees S and more strongly over South Africa. The spatial analysis of precipitation over the studied region shows that in most models the distribution of biases appears to be linked to orography. Wet biases are quasi-systematic in regions with higher elevation with inversely neutral to dry biases particularly in the coastal fringes. This spatial pattern of biases is particularly obvious during summer and specifically at the beginning of the rainy season (November and December) when the wet biases are found to be the strongest across all models. Applying a k-means algorithm, a classification of annual cycles is performed using observed precipitation data, and is compared with those derived from modeled data. It is found that the in-homogeneity of the spatial and temporal distribution of biases tends to impact the modeled seasonality of precipitation. Generally, the pattern of rainfall seasonality in the ensemble mean of the 10 RCMs tends to be shifted to the southwest. This spatial shift is mainly linked to a strong overestimation of convective precipitation at the beginning of the rainy season over the plateau inducing an early annual peak and to an underestimation of stratiform rainfall in winter and spring over southwestern South Africa.

  • 32. Prein, A. F.
    et al.
    Gobiet, A.
    Truhetz, H.
    Keuler, K.
    Goergen, K.
    Teichmann, C.
    Maule, C. Fox
    van Meijgaard, E.
    Deque, M.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Vautard, R.
    Colette, A.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jacob, D.
    Precipitation in the EURO-CORDEX 0.11 degrees and 0.44 degrees simulations: high resolution, high benefits?2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 1-2, p. 383-412Article in journal (Refereed)
    Abstract [en]

    In the framework of the EURO-CORDEX initiative an ensemble of European-wide high-resolution regional climate simulations on a 0.11 degrees (similar to 12.5 km) grid has been generated. This study investigates whether the fine-gridded regional climate models are found to add value to the simulated mean and extreme daily and sub-daily precipitation compared to their coarser-gridded 0.44 degrees (similar to 50 km) counterparts. Therefore, pairs of fine-and coarse-gridded simulations of eight reanalysis-driven models are compared to fine-gridded observations in the Alps, Germany, Sweden, Norway, France, the Carpathians, and Spain. A clear result is that the 0.11 degrees simulations are found to better reproduce mean and extreme precipitation for almost all regions and seasons, even on the scale of the coarser-gridded simulations (50 km). This is primarily caused by the improved representation of orography in the 0.11 degrees simulations and therefore largest improvements can be found in regions with substantial orographic features. Improvements in reproducing precipitation in the summer season appear also due to the fact that in the fine-gridded simulations the larger scales of convection are captured by the resolved-scale dynamics. The 0.11 degrees simulations reduce biases in large areas of the investigated regions, have an improved representation of spatial precipitation patterns, and precipitation distributions are improved for daily and in particular for 3 hourly precipitation sums in Switzerland. When the evaluation is conducted on the fine (12.5 km) grid, the added value of the 0.11 degrees models becomes even more obvious.

  • 33. Klutse, Nana Ama Browne
    et al.
    Sylla, Mouhamadou Bamba
    Diallo, Ismaila
    Sarr, Abdoulaye
    Dosio, Alessandro
    Diedhiou, Arona
    Kamga, Andre
    Lamptey, Benjamin
    Ali, Abdou
    Gbobaniyi, Emiola O.
    Owusu, Kwadwo
    Lennard, Christopher
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    Daily characteristics of West African summer monsoon precipitation in CORDEX simulations2016In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 123, no 1-2, p. 369-386Article in journal (Refereed)
    Abstract [en]

    We analyze and intercompare the performance of a set of ten regional climate models (RCMs) along with the ensemble mean of their statistics in simulating daily precipitation characteristics during the West African monsoon (WAM) period (June-July-August-September). The experiments are conducted within the framework of the COordinated Regional Downscaling Experiments for the African domain. We find that the RCMs exhibit substantial differences that are associated with a wide range of estimates of higher-order statistics, such as intensity, frequency, and daily extremes mostly driven by the convective scheme employed. For instance, a number of the RCMs simulate a similar number of wet days compared to observations but greater rainfall intensity, especially in oceanic regions adjacent to the Guinea Highlands because of a larger number of heavy precipitation events. Other models exhibit a higher wet-day frequency but much lower rainfall intensity over West Africa due to the occurrence of less frequent heavy rainfall events. This indicates the existence of large uncertainties related to the simulation of daily rainfall characteristics by the RCMs. The ensemble mean of the indices substantially improves the RCMs' simulated frequency and intensity of precipitation events, moderately outperforms that of the 95th percentile, and provides mixed benefits for the dry and wet spells. Although the ensemble mean improved results cannot be generalized, such an approach produces encouraging results and can help, to some extent, to improve the robustness of the response of the WAM daily precipitation to the anthropogenic greenhouse gas warming.

  • 34.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Regional Arctic sea ice variations as predictor for winter climate conditions2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 1-2, p. 317-337Article in journal (Refereed)
    Abstract [en]

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  • 35. Cerezo-Mota, Ruth
    et al.
    Cavazos, Tereza
    Arritt, Raymond
    Torres-Alavez, Abraham
    Sieck, Kevin
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Moufouma-Okia, Wilfram
    Antonio Salinas-Prieto, Jose
    CORDEX-NA: factors inducing dry/wet years on the North American Monsoon region2016In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 36, no 2, p. 824-836Article in journal (Refereed)
    Abstract [en]

    The output of four regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX)-North America (NA) region was analysed for the 1990-2008 period, with particular interest on the mechanisms associated with wet and dry years over the North American Monsoon (NAM) core region. All RCMs (RCA3.5, HadGEM3-RA, REMO, and RegCM4) were forced by the ERA-Interim reanalysis. Model precipitation was compared against several observational gridded data sets at different time scales. Most RCMs capture well the annual cycle of precipitation and outperform ERA-Interim, which is drier than the observations. RCMs underestimate (overestimate) the precipitation over the coastal plains (mountains) and have some problems to reproduce the interannual variability of the monsoon. To further investigate this, two extreme summers that showed the largest consistency among observations and RCMs were chosen: one wet (1990) and one dry (2005). The impact of the passage of tropical cyclones, the size of the Western Hemisphere Warm Pool (WHWP), the Intertropical Convergence Zone (ITCZ) position, and the initial intensity of the land-sea thermal contrast (LSTC) were analysed. During the wet year, the LSTC was stronger than the 2005 dry monsoon season and there were a larger number of hurricanes near the Gulf of California, the WHWP was more extended, and the ITCZ was located in a more northerly position than in 2005. All these processes contributed to a wetter NAM season. During the dry year, the LSTC was weaker, with a later onset, probably due to a previous very wet winter. The inverse precipitation relationship between winter and summer in the monsoon region was well captured by most of the RCMs. RegCM4 showed the largest biases and HadGEM3-RA the smallest ones.

  • 36.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jansson, Christer
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    CORDEX scenarios for Europe from the Rossby Centre regional climate model RCA42015Report (Other academic)
    Abstract [en]

    This report documents Coordinated Regional Downscaling Experiment (CORDEX) climate model simulations at 50 km horizontal resolution over Europe with the Rossby Centre regional atmospheric model (RCA4) for i) a ERA-Interim-driven (ERAINT) simulation used to evaluate model performance in the recent past climate, ii) historical simulations of the recent decades with forcing from nine different global climate models (GCMs) and iii) future scenarios RCP 4.5 and RCP 8.5 forced by the same nine different GCMs. Those simulations represent a subset of all CORDEX simulations produced at the Rossby Centre and a general conclusion drawn at the Rossby Centre is that such large ensembles could not have been produced without the establishment of an efficient production chain as outlined here. The first part of this report documents RCA4 and its performance in a perfect boundary simulation where ERAINT was downscaled. RCA4 is to a large extent replicating the large-scale circulation in ERAINT, but some local biases in mean sea level pressure appear. In general the seasonal cycles of temperature and precipitation are simulated in relatively close agreement to observations. Some biases occur, such as too much precipitation in northern Europe and too little in the south. In winter, there is also too much precipitation in eastern Europe. Temperatures are generally biased low in northern Europe and in the Mediterranean region in winter while overestimated temperatures are seen in southeastern Europe in winter and in the Mediterranean area in summer. RCA4 performs generally well when simulating the recent past climate taking boundary conditions from the GCMs. A large part of the RCA4 simulated climate is attributed to the driving GCMs, but RCA4 creates its own climate inside the model domain and adds details due to higher resolution. All nine downscaled GCMs share problems in their representation of the large-scale circulation in winter. This feature is inherited in RCA4. The biases in large-scale circulation induce some biases in temperature and precipitation in RCA4. The climate change signal in the RCP 4.5 and RCP 8.5 ensembles simulated by RCA4 is very similar to what has been presented previously. Both scenarios RCP 4.5 and RCP 8.5 project Europe to be warmer in the future. In winter the warming is largest in northern Europe and in summer in southern Europe. The summer maximum daily temperature increases in a way similar to summer temperature, but somewhat more in southern Europe. The winter minimum daily temperature in northern Europe is the temperature that changes the most. Precipitation is projected to increase in all seasons in northern Europe and decrease in southern Europe. The largest amount of rainfall per day (and per seven day period) is projected to increase in almost all of Europe and in all seasons. At the same time the longest period without precipitation is projected to be longer in southern Europe. Small changes in mean wind speed are generally projected. There are, however, regions with significant changes in wind. The ensemble approach is a way to describe the uncertainties in the scenarios, but there are other possible ensembles using other models which would give other results. Still, the ensemble used here is found to be similar enough to these other possible ensembles to be representative of the whole set of GCMs. Dynamical downscaling using RCA4 changes the climate change signal, and the ensemble spread is sometimes reduced, but the ensemble of nine RCA4 simulations, using different GCMs, is considered to be representative of the full ensemble. All scenarios agree on a climate change pattern; the amplitude of the change is determined by the choice of scenario. The relative importance of the chosen scenario increases with time.

  • 37. Jerez, Sonia
    et al.
    Tobin, Isabelle
    Vautard, Robert
    Pedro Montavez, Juan
    Maria Lopez-Romero, Jose
    Thais, Francoise
    Bartok, Blanka
    Christensen, Ole Bossing
    Colette, Augustin
    Deque, Michel
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Kotlarski, Sven
    van Meijgaard, Erik
    Teichmann, Claas
    Wild, Martin
    The impact of climate change on photovoltaic power generation in Europe2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 10014Article in journal (Refereed)
    Abstract [en]

    Ambitious climate change mitigation plans call for a significant increase in the use of renewables, which could, however, make the supply system more vulnerable to climate variability and changes. Here we evaluate climate change impacts on solar photovoltaic (PV) power in Europe using the recent EURO-CORDEX ensemble of high-resolution climate projections together with a PV power production model and assuming a well-developed European PV power fleet. Results indicate that the alteration of solar PV supply by the end of this century compared with the estimations made under current climate conditions should be in the range (-14%; +2%), with the largest decreases in Northern countries. Temporal stability of power generation does not appear as strongly affected in future climate scenarios either, even showing a slight positive trend in Southern countries. Therefore, despite small decreases in production expected in some parts of Europe, climate change is unlikely to threaten the European PV sector.

  • 38. Navarro-Ortega, Alicia
    et al.
    Acuna, Vicenc
    Bellin, Alberto
    Burek, Peter
    Cassiani, Giorgio
    Choukr-Allah, Redouane
    Doledec, Sylvain
    Elosegi, Arturo
    Ferrari, Federico
    Ginebreda, Antoni
    Grathwohl, Peter
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Rault, Philippe Ker
    Kok, Kasper
    Koundouri, Phoebe
    Ludwig, Ralf Peter
    Merz, Ralf
    Milacic, Radmila
    Munoz, Isabel
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Paniconi, Claudio
    Paunovic, Momir
    Petrovic, Mira
    Sabater, Laia
    Sabater, Sergi
    Skoulikidis, Nikolaos Th.
    Slob, Adriaan
    Teutsch, Georg
    Voulvoulis, Nikolaos
    Barcelo, Damia
    Managing the effects of multiple stressors on aquatic ecosystems under water scarcity. The GLOBAQUA project2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 503, p. 3-9Article in journal (Refereed)
    Abstract [en]

    Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerage, and policy advocacy. GLOBAQUA studies six river basins (Ebro, Adige, Sava, Evrotas, Anglian and Souss Massa) affected by water scarcity, and aims to answer the following questions: how does water scarcity interact with other existing stressors in the study river basins? How will these interactions change according to the different scenarios of future global change? Which will be the foreseeable consequences for river ecosystems? How will these in turn affect the services the ecosystems provide? How should management and policies be adapted to minimise the ecological, economic and societal consequences? These questions will be approached by combining data-mining, field- and laboratory-based research, and modelling. Here, we outline the general structure of the project and the activities to be conducted within the fourteen work-packages of GLOBAQUA. (C) 2014 The Authors. Published by Elsevier B.V.

  • 39. Stensgaard, A. -S
    et al.
    Booth, M.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Mccreesh, N.
    Combining a process-based and correlative approach to predict the impacts of climate change on schistosomiasis in eastern Africa2015In: Tropical medicine & international health, ISSN 1360-2276, E-ISSN 1365-3156, Vol. 20, p. 436-436Article in journal (Refereed)
  • 40. Guettler, Ivan
    et al.
    Stepanov, Igor
    Brankovic, Cedo
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Impact of Horizontal Resolution on Precipitation in Complex Orography Simulated by the Regional Climate Model RCA3*2015In: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 143, no 9, p. 3610-3627Article in journal (Refereed)
    Abstract [en]

    The hydrostatic regional climate model RCA, version 3 (RCA3), of the Swedish Meteorological and Hydrological Institute was used to dynamically downscale ERA-40 and the ECMWF operational analysis over a 22-yr period. Downscaling was performed at four horizontal resolutions-50, 25, 12.5, and 6.25 km-over an identical European domain. The model-simulated precipitation is evaluated against high-resolution gridded observational precipitation datasets over Switzerland and southern Norway, regions that are characterized by complex orography and distinct climate regimes. RCA3 generally overestimates precipitation over high mountains: during winter and summer over Switzerland and during summer over central-southern Norway. In the summer, this is linked with a substantial contribution of convective precipitation to the total precipitation errors, especially at the coarser resolutions (50 and 25 km). A general improvement in spatial correlation coefficients between simulated and observed precipitation is observed when the horizontal resolution is increased from 50 to 6 km. The 95th percentile spatial correlation coefficients during winter are much higher for southern Norway than for Switzerland, indicating that RCA3 is more successful at reproducing a relatively simple west-to-east precipitation gradient over southern Norway than a much more complex and variable precipitation distribution over Switzerland. The 6-km simulation is not always superior to the other simulations, possibly indicating that the model dynamical and physical configuration at this resolution may not have been optimal. However, a general improvement in simulated precipitation with increasing resolution supports further use and application of high spatial resolutions in RCA3.

  • 41. McCreesh, Nicky
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Booth, Mark
    Predicting the effects of climate change on Schistosoma mansoni transmission in eastern Africa2015In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 8, article id 4Article in journal (Refereed)
    Abstract [en]

    Background: Survival and fitness attributes of free-living and sporocyst schistosome life-stages and their intermediate host snails are sensitive to water temperature. Climate change may alter the geographical distribution of schistosomiasis by affecting the suitability of freshwater bodies for hosting parasite and snail populations. Methods: We have developed an agent-based model of the temperature-sensitive stages of the Schistosoma mansoni and intermediate host snail lifecycles. The model was run using low, moderate and high warming climate projections over eastern Africa. For each climate projection, eight model scenarios were used to determine the sensitivity of predictions to different relationships between air and water temperature, and different snail mortality rates. Maps were produced showing predicted changes in risk as a result of increasing temperatures over the next 20 and 50 years. Results: Baseline model output compared to prevalence data indicates suitable temperatures are necessary but not sufficient for both S. mansoni transmission and high infection prevalences. All else being equal, infection risk may increase by up to 20% over most of eastern Africa over the next 20 and 50 years. Increases may be higher in Rwanda, Burundi, south-west Kenya and eastern Zambia, and S. mansoni may become newly endemic in some areas. Results for 20-year projections are robust to changes in simulated intermediate host snail habitat conditions. There is greater uncertainty about the effects of different habitats on changes in risk in 50 years' time. Conclusions: Temperatures are likely to become suitable for increased S. mansoni transmission over much of eastern Africa. This may reduce the impact of control and elimination programmes. S. mansoni may also spread to new areas outside existing control programmes. We call for increased surveillance in areas defined as potentially suitable for emergent transmission.

  • 42.
    Gbobaniyi, Bode
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Sarr, Abdoulaye
    Sylla, Mouhamadou Bamba
    Diallo, Ismaila
    Lennard, Chris
    Dosio, Alessandro
    Dhiediou, Arona
    Kamga, Andre
    Klutse, Nana Ama Browne
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lamptey, Benjamin
    Climatology, annual cycle and interannual variability of precipitation and temperature in CORDEX simulations over West Africa2014In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 34, no 7, p. 2241-2257Article, review/survey (Refereed)
    Abstract [en]

    We examine the ability of an ensemble of 10 Regional Climate Models (RCMs), driven by ERA-Interim reanalysis, in skillfully reproducing key features of present-day precipitation and temperature (1990-2008) over West Africa. We explore a wide range of time scales spanning seasonal climatologies, annual cycles and interannual variability, and a number of spatial scales covering the Sahel, the Gulf of Guinea and the entire West Africa. We find that the RCMs show acceptable performance in simulating the spatial distribution of the main precipitation and temperature features. The occurrence of the West African Monsoon jump, the intensification and northward shift of the Saharan Heat Low (SHL), during the course of the year, are shown to be realistic in most RCMs. They also capture the mean annual cycle of precipitation and temperature, including, single and double-peaked rainy seasons, in terms of timing and amplitude over the homogeneous sub-regions. However, we should emphasize that the RCMs exhibit some biases, which vary considerably in both magnitude and spatial extent from model to model. The interannual variability of seasonal anomalies is best reproduced in temperature rather than precipitation. The ensemble mean considerably improves the skill of most of the individual RCMs. This highlights the importance of performing multi-model assessment in properly estimating the response of the West African climate to global warming at seasonal, annual and interannual time scales.

  • 43. Jacob, Daniela
    et al.
    Petersen, Juliane
    Eggert, Bastian
    Alias, Antoinette
    Christensen, Ole Bossing
    Bouwer, Laurens M.
    Braun, Alain
    Colette, Augustin
    Deque, Michel
    Georgievski, Goran
    Georgopoulou, Elena
    Gobiet, Andreas
    Menut, Laurent
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Haensler, Andreas
    Hempelmann, Nils
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Keuler, Klaus
    Kovats, Sari
    Kroener, Nico
    Kotlarski, Sven
    Kriegsmann, Arne
    Martin, Eric
    van Meijgaard, Erik
    Moseley, Christopher
    Pfeifer, Susanne
    Preuschmann, Swantje
    Radermacher, Christine
    Radtke, Kai
    Rechid, Diana
    Rounsevell, Mark
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Somot, Samuel
    Soussana, Jean-Francois
    Teichmann, Claas
    Valentini, Riccardo
    Vautard, Robert
    Weber, Bjorn
    Yiou, Pascal
    EURO-CORDEX: new high-resolution climate change projections for European impact research2014In: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 14, no 2, p. 563-578Article in journal (Refereed)
    Abstract [en]

    A new high-resolution regional climate change ensemble has been established for Europe within the World Climate Research Program Coordinated Regional Downscaling Experiment (EURO-CORDEX) initiative. The first set of simulations with a horizontal resolution of 12.5 km was completed for the new emission scenarios RCP4.5 and RCP8.5 with more simulations expected to follow. The aim of this paper is to present this data set to the different communities active in regional climate modelling, impact assessment and adaptation. The EURO-CORDEX ensemble results have been compared to the SRES A1B simulation results achieved within the ENSEMBLES project. The large-scale patterns of changes in mean temperature and precipitation are similar in all three scenarios, but they differ in regional details, which can partly be related to the higher resolution in EURO-CORDEX. The results strengthen those obtained in ENSEMBLES, but need further investigations. The analysis of impact indices shows that for RCP8.5, there is a substantially larger change projected for temperature-based indices than for RCP4.5. The difference is less pronounced for precipitation-based indices. Two effects of the increased resolution can be regarded as an added value of regional climate simulations. Regional climate model simulations provide higher daily precipitation intensities, which are completely missing in the global climate model simulations, and they provide a significantly different climate change of daily precipitation intensities resulting in a smoother shift from weak to moderate and high intensities.

  • 44. Vautard, Robert
    et al.
    Gobiet, Andreas
    Sobolowski, Stefan
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Stegehuis, Annemiek
    Watkiss, Paul
    Mendlik, Thomas
    Landgren, Oskar
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Teichmann, Claas
    Jacob, Daniela
    The European climate under a 2 degrees C global warming2014In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 9, no 3, article id 034006Article in journal (Refereed)
    Abstract [en]

    A global warming of 2 degrees C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change. The possible changes in regional climate under this target level of global warming have so far not been investigated in detail. Using an ensemble of 15 regional climate simulations downscaling six transient global climate simulations, we identify the respective time periods corresponding to 2 degrees C global warming, describe the range of projected changes for the European climate for this level of global warming, and investigate the uncertainty across the multi-model ensemble. Robust changes in mean and extreme temperature, precipitation, winds and surface energy budgets are found based on the ensemble of simulations. The results indicate that most of Europe will experience higher warming than the global average. They also reveal strong distributional patterns across Europe, which will be important in subsequent impact assessments and adaptation responses in different countries and regions. For instance, a North-South (West-East) warming gradient is found for summer (winter) along with a general increase in heavy precipitation and summer extreme temperatures. Tying the ensemble analysis to time periods with a prescribed global temperature change rather than fixed time periods allows for the identification of more robust regional patterns of temperature changes due to removal of some of the uncertainty related to the global models' climate sensitivity.

  • 45. Kotlarski, S.
    et al.
    Keuler, K.
    Christensen, O. B.
    Colette, A.
    Deque, M.
    Gobiet, A.
    Goergen, K.
    Jacob, D.
    Luethi, D.
    van Meijgaard, E.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Schaer, C.
    Teichmann, C.
    Vautard, R.
    Warrach-Sagi, K.
    Wulfmeyer, V.
    Regional climate modeling on European scales: a joint standard evaluation of the EURO-CORDEX RCM ensemble2014In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 7, no 4, p. 1297-1333Article in journal (Refereed)
    Abstract [en]

    EURO-CORDEX is an international climate downscaling initiative that aims to provide high-resolution climate scenarios for Europe. Here an evaluation of the ERA-Interim-driven EURO-CORDEX regional climate model (RCM) ensemble is presented. The study documents the performance of the individual models in representing the basic spatiotemporal patterns of the European climate for the period 1989-2008. Model evaluation focuses on near-surface air temperature and precipitation, and uses the E-OBS data set as observational reference. The ensemble consists of 17 simulations carried out by seven different models at grid resolutions of 12 km (nine experiments) and 50 km (eight experiments). Several performance metrics computed from monthly and seasonal mean values are used to assess model performance over eight subdomains of the European continent. Results are compared to those for the ERA40-driven ENSEMBLES simulations. The analysis confirms the ability of RCMs to capture the basic features of the European climate, including its variability in space and time. But it also identifies nonnegligible deficiencies of the simulations for selected metrics, regions and seasons. Seasonally and regionally averaged temperature biases are mostly smaller than 1.5 degrees C, while precipitation biases are typically located in the +/- 40% range. Some bias characteristics, such as a predominant cold and wet bias in most seasons and over most parts of Europe and a warm and dry summer bias over southern and southeastern Europe reflect common model biases. For seasonal mean quantities averaged over large European subdomains, no clear benefit of an increased spatial resolution (12 vs. 50 km) can be identified. The bias ranges of the EURO-CORDEX ensemble mostly correspond to those of the ENSEMBLES simulations, but some improvements in model performance can be identified (e. g., a less pronounced southern European warm summer bias). The temperature bias spread across different configurations of one individual model can be of a similar magnitude as the spread across different models, demonstrating a strong influence of the specific choices in physical parameterizations and experimental setup on model performance. Based on a number of simply reproducible metrics, the present study quantifies the currently achievable accuracy of RCMs used for regional climate simulations over Europe and provides a quality standard for future model developments.

  • 46. Walther, Alexander
    et al.
    Jeong, Jee-Hoon
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Chen, Deliang
    Evaluation of the warm season diurnal cycle of precipitation over Sweden simulated by the Rossby Centre regional climate model RCA32013In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 119, p. 131-139Article in journal (Refereed)
    Abstract [en]

    This study examines the diurnal cycle of precipitation over Sweden for the warm season (April to September) both in hourly observational data and in simulations from the Rossby Centre regional climate model (RCA3). A series of parallel long-term simulations of RCA3 with different horizontal resolutions - 50, 25, 12, and 6 km - were analyzed to investigate the sensitivity of the model's horizontal resolution to the simulated diurnal cycle of precipitation. Overall, a clear distinction between an afternoon peak for inland stations and an early morning peak for stations along the Eastern coast is commonly found both in observation and model results. However, the diurnal cycle estimated from the model simulations show too early afternoon peaks with too large amplitude compared to the observation. Increasing horizontal model resolution tends to reduce this bias both in peak timing and amplitude, but this resolution effect seems not to be monotonic; this is clearly seen only when comparing coarser resolution results with the 6 km resolution result. As the resolution increases, the peak timing and amplitude of the diurnal cycle of resolved large-scale precipitation become more similar to the observed cycle of total precipitation while the contribution of subgrid scale convective precipitation to the total precipitation decreases. An increase in resolution also tends to reduce too much precipitation of relatively light intensity over inland compared to the observation, which may also contribute to the more realistic simulation of the afternoon peak in convective precipitation. (C) 2011 Elsevier B.V. All rights reserved.

  • 47. Taylor, Christopher M.
    et al.
    Birch, Cathryn E.
    Parker, Douglas J.
    Dixon, Nick
    Guichard, Francoise
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lister, Grenville M. S.
    Modeling soil moisture-precipitation feedback in the Sahel: Importance of spatial scale versus convective parameterization2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 23, p. 6213-6218Article in journal (Refereed)
    Abstract [en]

    Feedback between soil moisture and precipitation influence climate variability in semiarid regions. However, serious concerns exist about the ability of coarse-scale global atmospheric models to depict one key aspect of the feedback loop, namely the sensitivity of daytime convection to soil moisture. Here we compare regional simulations using a single model, run at different spatial resolutions, and with convective parameterizations switched on or off against Sahelian observations. Convection-permitting simulations at 4 and 12 km capture the observed relationships between soil moisture and convective triggering, emphasizing the importance of surface-driven mesoscale dynamics. However, with the inclusion of the convection scheme at 12 km, the behavior of the model fundamentally alters, switching from negative to positive feedback. Similar positive feedback is found in 9 out of 10 Regional Climate Models run at 50 km. These results raise questions about the accuracy of the feedback in regional models based on current convective parameterizations.

  • 48. Vautard, Robert
    et al.
    Gobiet, Andreas
    Jacob, Daniela
    Belda, Michal
    Colette, Augustin
    Deque, Michel
    Fernandez, Jesus
    Garcia-Diez, Markel
    Goergen, Klaus
    Guettler, Ivan
    Halenka, Tomas
    Karacostas, Theodore
    Katragkou, Eleni
    Keuler, Klaus
    Kotlarski, Sven
    Mayer, Stephanie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Patarcic, Mirta
    Scinocca, John
    Sobolowski, Stefan
    Suklitsch, Martin
    Teichmann, Claas
    Warrach-Sagi, Kirsten
    Wulfmeyer, Volker
    Yiou, Pascal
    The simulation of European heat waves from an ensemble of regional climate models within the EURO-CORDEX project2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 41, no 9-10, p. 2555-2575Article in journal (Refereed)
    Abstract [en]

    The ability of a large ensemble of regional climate models to accurately simulate heat waves at the regional scale of Europe was evaluated. Within the EURO-CORDEX project, several state-of-the art models, including non-hydrostatic meso-scale models, were run for an extended time period (20 years) at high resolution (12 km), over a large domain allowing for the first time the simultaneous representation of atmospheric phenomena over a large range of spatial scales. Eight models were run in this configuration, and thirteen models were run at a classical resolution of 50 km. The models were driven with the same boundary conditions, the ERA-Interim re-analysis, and except for one simulation, no observations were assimilated in the inner domain. Results, which are compared with daily temperature and precipitation observations (ECA&D and E-OBS data sets) show that, even forced by the same re-analysis, the ensemble exhibits a large spread. A preliminary analysis of the sources of spread, using in particular simulations of the same model with different parameterizations, shows that the simulation of hot temperature is primarily sensitive to the convection and the microphysics schemes, which affect incoming energy and the Bowen ratio. Further, most models exhibit an overestimation of summertime temperature extremes in Mediterranean regions and an underestimation over Scandinavia. Even after bias removal, the simulated heat wave events were found to be too persistent, but a higher resolution reduced this deficiency. The amplitude of events as well as the variability beyond the 90th percentile threshold were found to be too strong in almost all simulations and increasing resolution did not generally improve this deficiency. Resolution increase was also shown to induce large-scale 90th percentile warming or cooling for some models, with beneficial or detrimental effects on the overall biases. Even though full causality cannot be established on the basis of this evaluation work, the drivers of such regional differences were shown to be linked to changes in precipitation due to resolution changes, affecting the energy partitioning. Finally, the inter-annual sequence of hot summers over central/southern Europe was found to be fairly well simulated in most experiments despite an overestimation of the number of hot days and of the variability. The accurate simulation of inter-annual variability for a few models is independent of the model bias. This indicates that internal variability of high summer temperatures should not play a major role in controlling inter-annual variability. Despite some improvements, especially along coastlines, the analyses conducted here did not allow us to generally conclude that a higher resolution is clearly beneficial for a correct representation of heat waves by regional climate models. Even though local-scale feedbacks should be better represented at high resolution, combinations of parameterizations have to be improved or adapted accordingly.

  • 49. Endris, Hussen Seid
    et al.
    Omondi, Philip
    Jain, Suman
    Lennard, Christopher
    Hewitson, Bruce
    Chang'a, Ladislaus
    Awange, J. L.
    Dosio, Alessandro
    Ketiem, Patrick
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    Stordal, Frode
    Tazalika, Lukiya
    Assessment of the Performance of CORDEX Regional Climate Models in Simulating East African Rainfall2013In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, no 21, p. 8453-8475Article, review/survey (Refereed)
    Abstract [en]

    This study evaluates the ability of 10 regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX) in simulating the characteristics of rainfall patterns over eastern Africa. The seasonal climatology, annual rainfall cycles, and interannual variability of RCM output have been assessed over three homogeneous subregions against a number of observational datasets. The ability of the RCMs in simulating large-scale global climate forcing signals is further assessed by compositing the El Nino-Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) events. It is found that most RCMs reasonably simulate the main features of the rainfall climatology over the three subregions and also reproduce the majority of the documented regional responses to ENSO and IOD forcings. At the same time the analysis shows significant biases in individual models depending on subregion and season; however, the ensemble mean has better agreement with observation than individual models. In general, the analysis herein demonstrates that the multimodel ensemble mean simulates eastern Africa rainfall adequately and can therefore be used for the assessment of future climate projections for the region.

  • 50. Kalognomou, Evangelia-Anna
    et al.
    Lennard, Christopher
    Shongwe, Mxolisi
    Pinto, Izidine
    Favre, Alice
    Kent, Michael
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    A Diagnostic Evaluation of Precipitation in CORDEX Models over Southern Africa2013In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, no 23, p. 9477-9506Article, review/survey (Refereed)
    Abstract [en]

    The authors evaluate the ability of 10 regional climate models (RCMs) to simulate precipitation over Southern Africa within the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework. An ensemble of 10 regional climate simulations and the ensemble average is analyzed to evaluate the models' ability to reproduce seasonal and interannual regional climatic features over regions of the subcontinent. All the RCMs use a similar domain, have a spatial resolution of 50 km, and are driven by the Interim ECMWF Re-Analysis (ERA-Interim; 1989-2008). Results are compared against a number of observational datasets.In general, the spatial and temporal nature of rainfall over the region is captured by all RCMs, although individual models exhibit wet or dry biases over particular regions of the domain. Models generally produce lower seasonal variability of precipitation compared to observations and the magnitude of the variability varies in space and time. Model biases are related to model setup, simulated circulation anomalies, and moisture transport. The multimodel ensemble mean generally outperforms individual models, with bias magnitudes similar to differences across the observational datasets. In the northern parts of the domain, some of the RCMs and the ensemble average improve the precipitation climate compared to that of ERA-Interim. The models are generally able to capture the dry (wet) precipitation anomaly associated with El Nino (La Nina) events across the region. Based on this analysis, the authors suggest that the present set of RCMs can be used to provide useful information on climate projections of rainfall over Southern Africa.

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